Cant select items seems like nothing is wrong but i might be doing someting wrong

[12588645]

Hi, I have seen some things where people were not able to select items but it seems to me that most of their issues were that they had it locked. However, I've checked this multiple times and it is not locked. I've also seen people say they may need to change the selection dropdown to all and i made sure it said all( which it does) 

My goal is to add an Arnold light to a mesh. This worked a couple days ago but now I can't select the items in my viewport and it's not letting me connect the Arnold light to the items in the list either. I'm not sure what to do and frankly I'm very frustrated because I need to get this done asap and have no idea what's going on.

Thanks for the help in advance

[RobH2]

So if you start a new file and make a cube or somehting, you then can't select it once you've clicked off of it? Is it that simple? Just asking some questions to know what to ask next. 

Have you tried an ENU reset and then tried to select in a new file?

https://www.autodesk.com/support/technical/article/caas/sfdcarticles/sfdcarticles/Resetting-3ds-Max-...

[Diffus3d]

It's possible the light expects a certain type of geometry (edit poly or mesh probably), so if you have modifiers on that object it may not see it as a valid selection.  Maybe collapse the stack on that object and see if that works.  

Best Regards,